The phrase "a key contributing" is correct and usable in written English.
It can be used when discussing factors or elements that play a significant role in a particular outcome or situation.
Example: "The research identified a key contributing factor to the success of the project."
Alternatives: "a major factor" or "a significant contributor."
A key contributing factor to early onset childhood is socialization to the eating and mealtime environment.
A key contributing feature in this last regard is acquiring agility with classifying in the domain (Leder et al. 2004).
A key contributing factor to the decline in revenues for small players may be the industry-wide transition to the upgraded 802.11ac standard access points, with 802.11n expected to be obsolete by the end of 2018.
Like previous assessments, the academy's report cites as a key contributing factor to the disaster the "failure of the plant owner [Tokyo Electric Power Co.] and the principal regulator [the Nuclear and Industrial Safety Agency] to protect critical safety equipment at the plant from flooding in spite of mounting evidence that the plant's current design basis for tsunamis was inadequate".
The resulting activation of cell proliferation could become a key contributing mechanism for the switch to androgen independence in prostate cancer.
The transmembrane span of HER2 has long been implicated as a key contributing factor to self-association and activation control.
Our data suggest that deprivation of glucose and inability of brain cells to process the glucose for bio-fuel production is an important key contributing mechanisms for neuronal degeneration in METH abusers.
Establishing the microfoundations of academic entrepreneurship requires closer scrutiny of a key actor contributing to this phenomenon the university scientist.
Lammy was one of a number of local politicians to endorse the report, which also cited high unemployment as a key factor contributing to the riots.
